This proposal addresses itself to the study of the brain mechanisms involved in visual pattern recognition and perception. Recently, we have discovered that it is possible to actually control the development of functional properties of single cells in the visual cortex of kittens by the simple device of controlling their visual experience. We have succeeded in demonstrating that the "shape" of all committed visual receptive fields in the visual cortex of controlled experience kittens is directly related to the shape of the visual stimuli they viewed during development. For some units the receptive field shape is a recognizable, though blurred, image of the stimulus! These findings form the bases for the proposed experiments. We intend to raise kittens in environments designed to engage different, specific aspects of visual perception. We expect that the kittens will have cells where functional characteristics will relate to specific features of the experience. This will enable us to relate function with mechanisms directly. We will further attempt to identify inborn versus experientially determined properties of single cells and networks. Finally, we will direct our investigation at measuring and tracing the connectivity of cells whose properties have been engendered by controlled experiences. The importance of this work may be assessed on both theoretical and practical grounds. From a theoretical standpoint, we are getting very close to memory mechanisms or at least their functional expression. From a practical standpoint, our findings indicate that we can actually control the development of the brain's functional structure in highly predictable ways. Could it be that children that are "retarded" would be helped by exposing them to appropriate structural experiences to aid them in developing the brain circuits that "normal" children must develop to be "normal"? It's much too early to say, but it's by increasing our understanding of how the brain wires itself together that we will increasingly be able to repair its disorders. Last, a real understanding of brain mechanisms will almost certainly, as a spin-off, further the development of data processing machines.